1. Technical Field
Aspects of the present invention relate to a print data generating apparatus, a printing apparatus, a method to generate print data, and a computer usable medium therefor, and more specifically, to an apparatus, a method, and a computer usable medium to generate print data which is suitable for printing an image in a plurality of inks including white ink.
2. Related Art
Conventionally, an inkjet printing apparatus, which ejects a plurality of colors of inks and white opaque ink onto a recording medium, has been known. In the inkjet printing apparatus, the inks are drawn from ink reservoirs to a plurality of ejecting channels provided in an inkjet head and ejected from nozzles at the end of the ejecting channels when actuators such as heater elements and piezoelectric elements are selectively activated. When an image is formed in colors, each of pixels composing the image is resolved, for example, into the three primary colors, which are cyan (C), magenta (M), and yellow (Y), thereafter, a colored pixel is formed as the inks adjusted in their densities are ejected onto the recording medium. In addition, a pixel in black is reproduced by blending the colored inks or using black (K) ink. Further, white (W) opaque ink can be used to reproduce white pixels and to form a base layer on a dark-colored (i.e., black) recording medium so that pixels in the three primary colors can be reproduced clearly over the base layer regardless of a color of the recording medium. Thus, images reproduced in higher quality can be obtained without being limited by colors and lightness of the recording media.
For the inkjet printer capable of printing in white, various methods to eliminate an effect of a color of the recording medium, which is substantially a background color of the printed image, have been suggested. For example, according to a method disclosed in Japanese Patent Provisional Publication No. 2002-46303, an image represented in RGB color format is logically inversed, and the white base layer is formed according to the inversed image data. Thereafter, the original image is formed on the base layer, i.e., the inversed image. For another example, in a method disclosed in Japanese Patent Provisional Publication No. 2005-103762, the image data is converted into grayscale data prior to a printing operation, and discharge printing is performed on the recording medium based on the inverted image.